Vibrations.

[Jason0411]

I have recently got my 1966 Lambretta back on the road. If any of you know anything about vintage two stroke engines you will realise they vibrate like a box of bumble bees in a rage.

I started commuting to and from work and my hip started to hurt from the inside to the outside. After five days I thought I would stop riding it and see how things went three days later no pain at all.
So in conclusion I can only put my pain down to the vibrations caused by my old Lambretta. I am going to try some larger engine mounts to see if I can reduce the vibrations and help but if not my Old Girl is going to have to go up for sale.

Has anyone else had problems with vibration?? Clean answers only please folks.

[Mike D]

Hi Jason
I've been wondering about this as well- I won't be back on my bike till spring but this last year when riding with increasing OA it was a real issue.
I've got a 1978 Suzuki GS1000, a big old air cooled brute, and like when your Lambretta was built, dampening the vibes was not the main concern.
It used to just get to my right hand-a foam grip and bar end weights helped a lot, but it then got to the hip so I've no idea what to expect when I get back out.
If you cure it, let me know how!

[imgetinold]

Jason......how far post-surgery are you (couldn't find a post that said so)?  If you're less than six months, or even a year, then perhaps you can just put it away for a year.  Whatever you're feeling now may completely resolve itself after a year.  Just a thought.

[Tin Soldier]

Good point Imgetin.  It could be similar to the clunking, in that as the muscles tighten, you have less "slop" in the new joint.  The more slop, early on, might accentuate vibrations from an outside source (ie older 2 stroke motorcycle).  Regardless, I think I would be hesitant to continue riding if the vibration and additional discomfort didn't go away.

[Spanielsal]

i was going to suggest a memory foam seat cushion - just a thin one.  worked for the astronauts!  might allow you to use the bike as things get better? 

might look quite funny    but if it gets you out and about.....

[David]

Hit the gym...start strengthening those glutes and adductors.  Your hip will be rock solid and you can "vibrate" forever!

[Jason0411]

Ho wtight have my glutes got to be? I already have buns of steel.

[John C]

I realize that it could not compete in the vibration category, but since my resurfacing, I have gotten back into riding after a 35 year layoff. I have a Yamaha V-twin. My resurfaced hip does not feel any problems at all, but my other arthritic hip does get very sore after about 45 minutes of riding. I did get the new bike until about two years after the surgery, which is about the point that long car rides stopped bothering my new hip. I am sure that you will grow past this issue.

[hernanu]

Ho wtight have my glutes got to be? I already have buns of steel.

Buns of steel... Pshaw.... steel only has compressive strength to about 400 MPA (N/mm²), Cobalt-chromium-Mb goes to 2068 MPA...

Jason, my man, you already have partially and need to get buns of cobalt-chromium... 

[Tin Soldier]

Nice engineery geakness Hern, thats awesome.    Regardless of buns of steel,.... or CoCr,... or what have you, I really wonder if the 50 to 100 um (I think) of spacing is the biggest issue.  If it is, then one would suspect, as Dave points out, that the tighter the muscles around the hip, the less ability for the prosthetic compounds to vibrate against each other.  If that is indeed what Jason is experiencing.   Picture a BHR out of the wrapper in the docs office, if you put one rubber band around the 2 components, then put the thing on top of a running washer machine, and see how clangy it is.  Then put 3 or 5 rubber bands around the components and do the same.  I would think you would have a lot less clanginess with the more rubber bands.  At a macroscopic level we assume the distance between the 2 is not much, we visualize them touching each other.  Although at a microscopic level, they don't really touch and syn fluid is all that separates them, so strong vibrations seem like they could easilly cause discomfort in a hip that has less tight muscles. 

What about harmonic oscillations?  Maybe there is some amount of harmonics going on, due to the component shape and material, and the motor frequency/RPM, it could then be additive. 

[hernanu]

Nice engineery geakness Hern, thats awesome.    Regardless of buns of steel,.... or CoCr,... or what have you, I really wonder if the 50 to 100 um (I think) of spacing is the biggest issue.  If it is, then one would suspect, as Dave points out, that the tighter the muscles around the hip, the less ability for the prosthetic compounds to vibrate against each other.  If that is indeed what Jason is experiencing.   Picture a BHR out of the wrapper in the docs office, if you put one rubber band around the 2 components, then put the thing on top of a running washer machine, and see how clangy it is.  Then put 3 or 5 rubber bands around the components and do the same.  I would think you would have a lot less clanginess with the more rubber bands.  At a macroscopic level we assume the distance between the 2 is not much, we visualize them touching each other.  Although at a microscopic level, they don't really touch and syn fluid is all that separates them, so strong vibrations seem like they could easilly cause discomfort in a hip that has less tight muscles. 

What about harmonic oscillations?  Maybe there is some amount of harmonics going on, due to the component shape and material, and the motor frequency/RPM, it could then be additive.

Good stuff Tin!!! Just the kind of geeky explanation that I love to hear...

The tighter the muscles, the less vibration and harmonic amplitude since the damping effect would come into play not just for the initial movement, but the harmonics as well. It would present a more consistent front for the synovial fluid to deal with, avoiding uneven compression of that layer.

Good golly I love good engineering talk  `.

[Jason0411]

Don't forget guys that I crushed my head by a centimetre, effectiveley making my internal elastic bands that much looser.

[Tin Soldier]

Good point Jason, better tighten up the rubber bands some more.   Hern - totally agree, less amplitude, less energy from harmonic oscillations.